Going Under
by KesslynB
Summary: Pandora/Linchpin AU. Picks up at the beginning of Linchpin.
1. Chapter 1

As the car plunged into the icy water, the force of the impact threw Beckett and Castle forward. For some reason, the airbags hadn't deployed with the initial impact, and now the seatbelts locking in place were the only thing keeping them from smashing face first into the dashboard. The car continued to sink, nose first, as water seeped in from the engine. Beckett could feel the cold water swirling around her ankles over the tops of her boots.

Beckett asked, turning towards her partner by instinct. There was some sunlight filtering through the murky water. "Castle, you okay?"

Castle nodded his head. "I'm fine." He tugged futilely on the door handle, pushing on the door with his shoulder. "My door won't open."

"It won't," Beckett replied calmly. "The water pressure is too great. We'll crawl into the backseat and then use my gun to shoot the rear window out. It's big enough for both of us to get out. The pressure will finish the job of breaking the glass and then we can swim to the surface."

She and Castle reached for their seatbelts as the water continued to rise past her calves to her knees. "Be careful when you release it. You'll pitch forward, so be prepared." She heard the decisive click of his, followed by the distinctive whoosh as it retracted. She pressed on hers, pulled on the belt, and then simply sat there in shock as it stayed in place. She jammed her thumb onto the latch a few times, trying not to draw attention to her movements.

Castle had started to crawl in between the seats when he realized she wasn't following him; or more accurately, taking the lead, as she so often did. She was still in her seat, which set off warning bells in his head.

He turned back to face his partner, and his voice rose in panic. "Beckett?"

She thought frantically. If she couldn't save herself, at least she could save Castle. "Castle, you go first and then I'll pass you my gun. You can shoot out the window. I'll follow you out."

The warning bells changed into sirens. Beckett never, ever volunteered to follow him. "What's wrong?"

"Nothing," she tried to reassure him. "We're running out of time." Which was true; the water was rising fast and was now at her waist. She pulled her gun out of the holster, keeping it out of the water. "We can't let my gun get wet or it might not fire. We need to hurry."

"As soon as you tell me what's wrong." He stared at her as he sat there between the two front seats, giving every impression of waiting until she caved.

_Stubborn, stubborn man!_ Realizing that arguing would be pointless and waste precious time, she conceded, "I'm stuck, okay? My seatbelt won't release."

"Damnit!" His fears realized, he jabbed the release with his thumb and yanked violently on the belt, cursing softly when it didn't give way. He pressed harder, tugging in every direction before Beckett stopped him.

"Castle," the water was now halfway up her chest, and the still-healing scar on her side started to contract and pulse in the cold. "Castle, you have to save yourself."

"I'm not going anywhere without you," he stated firmly, shaking his head, refusing to even consider the idea.

"Rick," she laid a hand on his forearm, momentarily stilling him. Their eyes met and Beckett was briefly transported back to that spring day in May when she lay on the grass, bleeding out. His eyes were once again roiling with those emotions, a mix of fear and love. To distract them both, she placed her gun in his hand. "My seatbelt is stuck. The seat controls are electrical, so they won't work. There's no way out for me. Just go."

"No!" He practically shouted. "There's always a way. Do you have a knife?" When she shook her head, he tried to quell his panic so he could think. "We'll just have to break the seat," his relief and having a solution was nearly palpable. "I'll get behind you and pull on it, while you push. Once the seat is broken, you can slide out, okay?"

The water was over her breasts, nearly to her neck. "Castle-" She started to protest, but she felt the seat being pulled on by her partner. "Castle, promise me if this doesn't work, you will get out. Think about Alexis and Martha. You have a family."

"So do you," he stated quietly. He wrapped one arm around the headrest and pulled as she pushed back against it. The seat gave way just enough. "Now, Kate!" he ordered, and she began to shimmy her way from under the lap belt, but the angle was awkward and she was only able to move a few inches.

Despite knowing the futility of it, she took a deep breath as the water closed over her head. She heard the muffled sound of two shots, followed by an immediate slackening of her seat belt. She renewed her effort to get free of the restraint. Three more shots went off and she felt the pressure from the water finishing the job of breaking the windshield. Glass and water rushed in to fill the car, and the icy water swirling around her caused her scar to throb painfully. She involuntarily gasped, swallowing a mouthful of river water. She choked and gagged, trying not to breathe in more, but it was too late.

As the darkness claimed her, she thought _Please, God, let Castle have made it out, _never feeling his hands grab her wrists, pulling her out from the seat and then wrapping an arm around her as he swam towards the surface.

~~CBCBCB~~

Castle spluttered as he broke the surface of the water, carrying an unresponsive Beckett with him. He made sure her face was above the water, before looking around for help

"Hey!" he shouted, trying to get someone's attention. He needed to get Beckett out of the water _now_. He started swimming one-handed towards the dock, his other arm wrapped around Beckett's chest under her arms. He had only made a few strokes when he heard the sound of a boat engine heading towards them at a high rate of speed. He stopped and waved one arm. "Hey! Help us!"

The boat pulled alongside him and before he realized what was going on, two bodies splashed into the water.

"Harbor Patrol." One of the rescuers announced himself. "We're here to help."

"Save Beckett. She's not breathing."

"We'll take care of her."

The next few minutes passed in a blur as they took Beckett from his arms, and hauled the both of them onto the deck. The next thing he heard clearly was her coughing a few feet away.

_Thank God!_ He crawled over to her, and the officer who had been performing mouth-to-mouth gave way to him. She was lying mostly on her back, with just her head and shoulders turned to the side. He helped her turn more fully onto her side and began rubbing circles on her back as she continued to cough up the river water. Just when he thought she was done, she pushed herself up a little, and crawled to the edge, hanging her head over the side of the boat and proceeded to throw up the remaining water she had swallowed.

One of the Harbor Patrol officers draped a blanket over his shoulders and set one down next to him. "For her," he explained.

Castle looked up at their rescuer. "Thank you." He unfolded the blanket and tenderly covered Beckett's back with it, making sure to keep it from falling in front of her while she was still vomiting.

Beckett's retching eased up, and she began gasping. "Castle?"

"I'm right here, Kate." He placed his hand over hers, attempting to reassure her.

She gripped his hand, squeezing tightly, still gasping and wincing with every breath. "Heating...pad…scar…"

Before Castle could ask, the officer pulled out a small object and handed it to him. "Here, use this until I find something. It's a hand warmer, but it'll do for now."

Castle took it gratefully as the officer stood up and headed into the cabin. Knowing that gentleness was not what was needed right now, he placed the warmer on Beckett's left side where the pain seemed to be originating and pressed down firmly.

"Higher," Beckett gasped, guiding him until it was placed directly over her scar. When the officer returned with a heating pad, Castle removed the warmer, replacing it with the pad. As the heat worked to relax the muscles that had contracted with the cold, her breathing gradually evened out.

The officer, who had been waiting patiently, finally spoke up. "We've got an ambulance on the way to the pier to check you out. You wanna tell me who you are?"

"I'm Detective Kate Beckett, out of the 12th, badge 41319. I need to call my team." Her voice was raspy, not a trace of her usual command.

The officer's demeanor softened. "We were in the area because we had reports of a car going into the river. That yours?"

This time, Castle answered, wanting to spare her the effort. "Yes. A black SUV rammed into us from behind and shoved us in. We're lucky we made it out alive."

The officer stood up again. "All right. I'll make some calls."

After he disappeared from their sight, Castle felt Beckett pulling her hand away from where it was still gripping his. His fingers tightened briefly before releasing her.

She sat up and attempted to drag one hand through her wet hair, before giving up. "Castle," she began, sounding very hesitant.

Castle opened his mouth to make a quip, defaulting to his coping mechanism of humor after the stress of another life or death situation. Beckett forestalled him. Her eyes bored into his, relaying the seriousness of her gratitude. "Thank you. You saved my life. I wouldn't have made it out without you."

"Hey, you're the one who said that's what partners do. You'd have done the same for me."

They spent the rest of the ride to the docks in silence.


	2. Chapter 2

After Harbor Patrol docked at the pier, Beckett was quickly hustled into the waiting ambulance, despite her protests that she was fine. When they were finished examining her, they released her with admonitions to see a doctor immediately if she started coughing or running a fever. She hopped out of the back of the ambulance, still in her wet clothes and wrapped in the blanket and found Castle pacing just outside the doors. He turned to her, but before he could even ask how she was, the EMTs were ushering him in, just as they had her. As the doors closed behind them, Beckett gave a small smile, and stepped away. She swept her gaze over the area and saw that Esposito had arrived with other units and a fire truck was parked nearby as well. Esposito had his back to her and was directing uniforms to secure the scene and to search for any witnesses.

Not wanting to disturb him, she turned towards the water, only to hear hi, shout "Beckett!" from behind her. She turned back and Esposito jerked a thumb towards his unit, parked nearby. "Trunk!" he instructed, before turning back to the uniforms and continuing to issue orders.

She went to his car, popped the trunk and gratefully took out a fleece-lined NYPD jacket and a grey NYPD t-shirt. She knew they would be a little big on her, but warm and dry trumped fit at the moment. The pants looked like a pair of hers and she wondered where he managed to get them from.

Grabbing the clothes, she slammed the trunk lid closed, and looked around for a place to change. Seeing that the only possibility was the ambulance, she made her way back to it and waited for Castle to emerge. While she was waiting, Lanie and Alexis arrived and after reassuring them both that she and Castle were fine, she directed them to Blakely's body. Lanie went to examine the body, but Alexis stayed with Beckett to wait for her father. When the EMTs released him, Alexis wrapped him in a bone-crushing hug before dragging him away give him the clothes she had brought. Beckett received permission from the EMTs to change in the ambulance and the EMTs tactfully withdrew and waited outside for her finish.

This time when she came out, Castle was nowhere to be seen and she assumed he was off somewhere, changing as well. She went to the edge of the pier and stared off into the water, trying to process everything that had happened. Castle had saved her life again, nearly at the expense of his own. _Stubborn man._ She was grateful, no doubt, but she was the cop. It was supposed to be her job to protect him, not the other way around. She had tried, but he wouldn't listen, wouldn't leave without her. _Stubborn man,_ she thought for the third time.

Lost in thought, she didn't hear Castle approaching from behind her until she heard him speak. "I guess the good thing about having a daughter at crime scenes is that she can bring you dry clothes," he stated. She turned to face him and noticed that not only had he changed, he also was carrying two to-go cups of coffee. She grinned and he handed Beckett one of the coffees.

She took it gratefully. "Thanks." She let the warmth of the coffee seep into her still-chilled fingers as she took a sip. It had cooled off enough to not scald her tongue, and she took an even larger gulp. She saluted him with the cup, and reiterated, "And, umm, thanks." She didn't clarify, knowing that he would understand what she was referring to.

"You'd have done the same for me," he replied, doing his own staring out over the water.

"Yeah, but let's not put that to the test, okay?"

"Yeah. That whole sinking car thing? Much cooler in movies than in real life," he confessed as he took a sip of his own coffee, trying for humor, but falling short.

Attempting to keep the light tone, she stated, "And for the record, I prefer watching spy thrillers to being in them."

"So." They were interrupted by Esposito, and they both turned to towards him. "Tell me. How can your victim look like Nelson Blakely, when he supposedly died ten years ago?"

They managed to deflect Esposito and were talking about Blakely to Lanie, Alexis, and Ryan when a black SUV pulled up and screeched to a halt. Sophia and Danberg got out, and Sophia slammed her door closed. The furious expression on her face did not bode well.

Castle hung his head and began to approach them when Beckett put her hand on his arm, forestalling him. She took an instinctive step forward and placed herself between Castle and Sophia.

"He's dead," Sofia declared, glaring daggers at Castle, completely ignoring the detective's presence. Before Castle could speak, Beckett came to Castle's defense, attempting to defuse the agent's anger. "I can explain."

Before she could finish, Sophia interrupted, still aiming that deadly gaze at Castle. "Get in the car," she ordered, turning back to the SUV, clearly expecting to be obeyed without question.

Beckett's eyes narrowed, and Danberg shrugged apologetically. She hesitated before following, but got into the backseat without protest, Castle right behind her.

* * *

The car was filled with tension, and they arrived back at the CIA without another word being spoken by anyone. They exited the elevator and Sophia immediately turned on Castle. Beckett tried to intervene, but Sophia was only focused on Castle.

After Castle and Beckett told her what they had learned from Blakely, Sophia's attack turned personal. "You know, I really thought you had changed. But you know what? You are the same reckless, immature, self-centered jackass you always were." The venomous words spewed forth and Sophia began to get into Castle's personal space.

Beckett had heard enough and once again put herself between her partner and the CIA agent. "He may be reckless on occasion," she defended him and could feel Castle's surprise even if he was behind her. "But if it weren't for him, we'd have never found Blakely, let alone learned anything about Pandora and this linchpin."

Sophia ignored the detective. "It was a mistake bringing you in. You put this investigation at risk. Get them both out of here," she ordered as she turned away, coldly dismissing them.

* * *

Beckett waited until they were in the privacy of the precinct elevator before she spoke again.

"She's wrong, you know."

"Hmm?" Castle questioned, and Beckett could tell he was still thinking about the confrontation with his former muse. "Sophia?"

She plowed forward anyway, needing to defend him, even if it was just between them. "Yes," Beckett confirmed. "You can be an immature, self-centered jackass on occasion, but she was wrong about one thing. You have changed."

When all he said was "Yeah", and continued to stare off into the distance, Beckett knew he hadn't really heard her and mentally sighed in defeat. Beckett wondered why Sophia's words had such an effect on Castle and the realization dawned on her.

"You slept with her," she stated out loud, and then winced, hoping Castle still wasn't paying attention.

Luck was not on her side, and he confirmed, "Yeah. Yeah, I slept with her."

A pang of jealousy shot through her. Sophia was his former muse and his former lover. As much as Beckett had originally hated it, she had always thought their situation was unique and then she learned that Sophia had been his muse and that he had followed her around the CIA, much as he was doing now with her at the precinct. And now he admitted that they had slept together as well. Her insecurities took a direct hit. She was just a cop, how was she supposed to compete with a CIA agent?

Attempting to mask her hurt, she went on the attack. "Have there been others?"

"Women?" Castle asked, surprised.

As often as he had bragged about it, she knew there had been other women. And to listen to him talk, there had been plenty. No, what she was focused on was the one thing she and Sophia had in common. "Muses."

"No," Castle responded. "Why?" He turned to her just as the elevator dinged and the doors opened, giving her a chance to escape.

Grateful for the opportunity to stride past him so he wouldn't see the hurt on her face, and unwilling to divulge the real reason she asked, she deflected, "Just wanted to see how big the club was, that's all." Attempting to forestall any comeback, she called out the boys. "Hey guys, what do you got?"

Castle stepped in front of her, forcing her to face him and listen. "First of all, there is no club." The sincerity in voice rang true, and she was momentarily taken aback. But before she could dwell on it, he continued. "And second of all, we're off the case," he pointed out.

As they moved through the precinct, they argued until Beckett realized that she had been so distracted by their back and forth that she had walked to the wrong desk. Fighting hard not to blush in embarrassment as Castle, who had been joined by Esposito and Ryan, stared at her with her hand on the back of someone else's chair. She tried to act nonchalant as she approached her own desk and asked the boys about the case to make sure they didn't say anything.

They talked about Blakely until Castle pointed out, "He plays chess. That's not a solo sport."

Her heart warmed at his input. "I thought you were off the case."

"As you said, we're off Sophia's case. I'm your partner. If you're stubborn enough to keep going, I'm stupid enough to go with you," he declared, shrugging in an attempt to downplay his words.

She fought back a smile before turning and giving directions to Ryan and Esposito. As they left, the phone rang and she picked it up. "Beckett."

It was Lanie calling to inform her that Blakely's body never arrived and she and Castle raced to the morgue to talk to Lanie in person.


End file.
